Lock nut



. 'ent portion and rushed on. 23, 1941] UNITED sm-r s PATENT OFF-ICE 1 Loon mrr Richard Waterman Luce, Westfleld, N. J. Application February 2, 1939, Serial No. 254.214:

t '6 Claims. 1 (Cl-.151-21-) The invention herein disclosed relates to a lock-nut of the type including a tapped body portion having 'the load carrying threads, an-

other tapped portion displaced from the body portion and a resilient portion between'the two tapped portions. Such a lock-nut .is disclosed in my United States Patent No. 2,196,637 'or' April 9, 1940.

The lock-nut disclosed in the aforementioned application is constructed from a single pieceof metal and consists of three portions, a tapped body portion having-the load carrying threads,

another, smaller tapped portion displaced from the body-portion, and a bellows-like resilientportion between the two tapped portions. Thebellows-like resilient portion consists of two, axially displaced, substantially radial wall sec 'tionsjoinedat their circumferential edges in a curved circumferential wall section. The smaller tapped portion is a tapped cylinder having an outer radius equal to the inner radius of the radial wall section of the resilient portion. The threadsbt the'nut are interrupted at the resili the threads of the two tapped portionsare normally out of phase such that portion-I a smaller tapped portion 2 axially displaced from the body portion and a bellowslike, resilient portion 3 uniting the two tapped portions. In the iinished'nut, the threads of the two tapped portions are out of phase. when the nut is screwed on a bolt, the bolt first enters the bodyportion and then the smaller tapped portion. On entering the smaller tapped portion,

it must" expand the bellows-like, resllient'portion until the threads thereof coinclde'with the threads'ot the bolt. The expanded-'bellows-like, resilient portion exerts a force tending to draw the two tapped portions together and'in consequence draws the threads of the body portion of the nut into frictional engagement with the threads of the bolt. This frictional force is sufflcient to prevent loosening of the nut on-the bolt by virtue oi forces resulting from vibration. v

The nut blank, shown in Fig. 1, is preferably cut from hexagonal bar stock. The body-portion of the nut retains the hexagonal configure-4 tion of the barstock. This portion of the nut 'from'the body portion and has formed thereon when a bolt passes onetapped portion and enters the other it causes the. resilient, bellows-like portion to expand. The load carrying threads of the body portion are thus caused to engage,

vin'iricti'onal contact, the threads of' the bolt.

This frictional force, between the threads of the nut and, the bolt, eflectivcly maintains the nut on the bolt against the loosening action of forces.

ofvlbration.

The invention herein disclosed has for an ob-' ject to provide a'lock-nut of this general type that has certain constructional advantages and features that render the lock-nut more adaptable and suitable to its intended function. The

lock-nut constructed in accordance with the invention includes a reinforced smaller tapped portion, a smooth frustro-conical surface for the bolt to act against in expanding the resilient portion of the lock-nut, and an arrangementand proportioning of the several portions .of the locknut for eflectlng a uniform action of the locknut and for facilitating its construction. A lock-nut embodying" the invention is disclosed in the accompanying drawing in which:

Fig. 1 is a longitudinal section of a blank prior to being tapped; and

Fig. 2 is a longitudinal nut.

The lock-nut illustrated in the drawing essen-' tion of the a reinforcing bead 2a.

has the load carrying threads la cuttherein.

The smaller tapped portion 2 is axially spaced The threads '21) formed in'this portion of the nut are formed at the sametime and with the same tap with which the threads of the body portion are formed. These threads are therefore identical with the threads of the body portion and-the threads of these two tapp'ed portions are in lead with respect to each other. The tap is run through the blank shown in Fig. 1 to form these threads and the reinforcing bead 2a prevents the smaller tapped portion from spreading as the tap goes through.

Without this bead 2a the smaller tapped portion has a tendency to spread and the threads thereof, are not always out uniformlyor to the Proper depth.

As more clearly seen at the inner end oi the smaller tapped portion, a

t n y. consists of threeportions, a tapped body 55 in Fig. 2, thereds formed, I

two, substantially radial wall sections 3a and 3b joined at their outer end by a curved circumferential wall section 30. The walls of the .bellows-like, resilient portion are of substantially uniform thickness and less than the wall thickness of the thinnest part of either tapped portion including the thread. At the inner end, the wall section 3c is joined in a smooth curve 3d of a single radius to the smaller tapped portion and the inner end of the wall section 3b is joined to the body portion in a smooth curve 3e of a single radius. Except for the point of unification of the wall section 3a to the smaller tapped portion and of the wall section 3b to the body portion, the bellows-like resilient portion is out of contact with the tapped portions. The wall sections 3a and 3b are spaced from the smaller tapped portion and the body portion respectively a distance at least equal to the thickness of the wall section, and they are spaced apart a distance greater than the thickness of a wall. section, ap-

proximately twice the thickness of a wall sec tion. This arrangement provides a free bellows like resilient section in which, the resiliency is primarily in the form of a bending moment about the arcuate circumferential wall section 30. A uniform axial force is thus provided upon expansion of the resilient portion. Preferably, the nut is made from a metal having from ten to twenty-five percent elongation, i. e. in .two inches at the ultimate strength, to provide the desirable workability and resiliency.

A nut such as that illustrated and described in detail above, provides a uniform axial force that causes, when the nut .is threaded on a bolt, the load carrying threads of the body portion to engage in frictional contact the threads of t a bolt. This force is exerted primarily as the result of a bending action, within the elastic limit of the material, of the wall section 30. In consequence, the bellows-like resilient portion has a greater range of movement before taking a set than would be the case were the action purely one of tension or compression. 'I'he'action of the resilient, bellows-like portion is such that irre-- spective of the tolerances, within the limits of commercial practice, in the threads of a nut and bolt it will be suficient to eflect a pressure contact at all times between the threads and the bolt upon which it is threaded. and the magnitude of the force exerted is such that it does not injure the th eads.-

When mad of steel, particularly of a low carbon steel, below 35 carbbn (0.35% carbon) and approximately 15 carbon (0,15% carbon), for example, the emcacy of the spring section may be greatly enhanced by case hardening and drawing the case to a spring temper. Steels of low carbon have the characteristic of high machinability. When the nuts made of such steel are case hardened to a depth of from 10 to 25% of the thickness of the wall section and drawn to a spring temper, the spring section has much greater resiliency. The depth of the case hardening will vary depending upon the type of case hardening, i. e. cyanide or carborized. Nuts of a higher carbon than 35 may be heat treated to enhance the characteristics and effectiveness of the spring section. I

If it be desired to reduce the weight of locknuts of this or similar types, 'as for example, when large quantities are used on airplane structures, the body of the nut may be turned down from the lower face to a point indicated by the line 4, leaving a diameter of this lower portion equal "to the face of the nut indicated by a continuation of the line 5. To further reduce the weight of the nut the section between the line 4 and a line 6 may be undercut to a depthrepresented by a continuation of a line I; The nut so cut down has the same facearea and the portion from the line 4 to the top' of'the body of the nut provides a hexagonal portion for applying a wrench to the nut. The strength of the nut, from the standpoint of its function is notmaterially altered by :the removal of this material and its weight is considerably reduced.

It will be obvious that various changes may be made by those skilled in the art in the details of the lock-nut illustrated in the drawing and described in detail above within the principle and scope of the invention as expressed in the I appended claims.

I claim:

I. A lock-nut comprising in a single piece of carrying threads therein, a smaller tapped por*' tion axially spaced from the body portion and having the threads thereof out of phase with .the

threads of the body portion, and a resilient portion between the two tapped portions i'ncluding spaced, substantially radialwall sections of substantiallyiuniform thickness, the nut being case hardened and the resilient portion drawn to a spring temper.

3. A lock-nut comprising in a single piece of steel, a.- tapped body portion having the load carrying threads therein, a smaller tapped portion axially spaced from the body portion and I having the threads thereof out of phase with the threads of the body portion, and a resilient portion between the two tapped portions includ ing spaced, substantially radial wall sections of substantially uniform thickness, the nut-being case hardened to a depth not exceeding twentyfive percent of the wall portion.

4. A lock nut comprising in combination a tapped body portion having the load carrying thickness of the resilient threads therein, a bellows-like resilient portion at I one end of the body portion including spaced,

substantially radial walls, one extending and spaced from the body portion and joined thereto in a smooth curve, a smaller tapped portion ,connected with the resilient portion and axially spaced from the body portion, the resilient, portion normally maintaining the two tapped portions with the threads thereof out of phase, and

a circumferential reinforcing bead on the smaller tapped portion extending radially outwardly'beyond the inner end orthe other radial wall of the resilient portion, axially spaced therefrom and joined thereto in a smooth curve.

5. Alock-nut comprising a tapped bo'dy portion having the load-carrying threads therein, a smaller tapped portion axially displaced from the body portioma resilient portion between the two v 2,260,581 H is 3 tapped portionsnormally maintaining the smallor tapped Portion positioned with respect to'the' body portion with the threads thereof out of phase in a direction towards the body portion,

and an internal smooth, conical,- pressure con-- nected with the resilient portion and axially spaced from the body portion, the resilient portion normally maintainingithetwo tapped portions with the threads thereof out of phase in a tact surface joining the resilient portion and the smaller tapped portion for engaging a bolt en tered in the nut and electing expansion of the resilient-portion to bring the thread thereof into coincidence with the thread on the bolt.-

1 a. lock-nut comprising i i ation atappedbody portion haying the load carryina threads therein, a bellows-like resilient portion at one end 01 the body portion including spaced.

direction towards the body portion, acircumfer- =entia1 reinforcing bead on the smaller tapped portion extending radially outwardly beyond the inner end of the other radial wall of the resilient. portion, axially spaced'therefrorn and joined thereto in a smooth curve, and an'internal smooth, conical, pressure contact surface joining the resilient portion and the smaller tapped portion for erig'aginga bolt entered in the nut and eflectins'expansion oi-the resilient portion to' bringthe thread thereof into coincidence with the thread on the bolt."

W. oon; t 

